The purpose of the current study was to know the histopathologic characteristics of those patients with clinical history of corneal ectasia secondary to refractive surgery in a large Mexican ophthalmologic referral center in a period of ten years (2004-2014).

Methods

A retrospective, observational, cross-sectional, descriptive study was performed. The slides of all corneal buttons stained with H&E, PAS and Masson’s trichrome from patients with history of corneal ectasia post refractive surgery treated with penetrating keratoplasty were evaluated. Microscopically, they were measured and photographed with the AxioVision 4.2.8 system.<br /> The variables studied in the corneal buttons were divided in two different categories: qualitative characteristics which were those alterations in each of the corneal layers and quantitative features, which included full corneal thickness and epithelial thickness. In LASIK cases other measures than flap, were stromal flap and the residual stromal bed thickness respectively. In cases of radiated keratotomy we also measured the epithelial thickness at the incision site and extent of epithelial projections through the stroma at the incision site.

Results

A total of 50 specimens from 47 patients were studied. The average of full corneal thickness at the greatest ectasia site was 344.83 microns and at the epithelium 38.06 microns. In the LASIK cases, the average thickness of the flap was 162.29 microns and 181.34 microns of the residual stromal bed. The most frequent findings were atrophy alternating with epithelial hyperplasia (62%), partial loss of Bowman’s layer (42%), decrease of residual stromal bed (73%) and endothelial loss (56%).

Conclusions

Alterations of the posterior layers such as decrease of the stromal bed and endothelial loss, are risk factors for corneal ectasia that were confirmed with our results. The current series showed additional anomalies of the anterior corneal layers.<br /> In addition to the posterior layers, the alterations of anterior layers increase the development of corneal ectasia.